Paroxetin, (xe2x80x94)-trans-4-(4xe2x80x2-fluorophenyl)-3-(3xe2x80x2,4xe2x80x2-methylenedioxyphenoxymethyl)-piperidine is described in U.S. Pat. No. 3,912,743 and U.S. Pat. No. 4,007,196 and is employed as an antidepressant. The usual form in which it is administered is the hydrochloride. For general pharmaceutical use and for the formulation of medicaments, the hemihydrate (xc2xdH2O) is the usual form.
EP-B-0 223 403 describes both the anhydrate and the hemihydrate. Also known are organic solvates, especially with 2-propanol, as described in WO-A-96/24595.
The above mentioned EP-B-0 223 403-describes the preparation of the anhydrate by sharply drying the hemihydrate; however, rehydratation to the hemihydrate occurs very quickly.
WO-A-98/31365 describes the preparation of a free-flowing and easily soluble form as a hemihydrate or solvate. The preparation of a taste-protected paroxetin according to WO-A-95/15155 is based on the use of a complex of the free bases with a copolymer of methacrylic acid and methyl methacrylic acid.
The preparation of a slow-release form is described in WO-A-96/31197 which refers to the use of paroxetin hydrochloride. A concrete example of paroxetin is not stated, but due to the auxiliaries employed for retardation which already contain a considerable amount of water and due to the melting process employed, only the hemihydrate or a higher hydrate can be formed according to the method described therein, even when the paroxetin hydrochloride anhydrate is employed.
Combinations of 5-hydroxytryptamine (5HT) uptake inhibitors (paroxetin, inter alia) with other active ingredients for achieving specific pharmacological and therapeutical effects are described in WO-A-96/41633, GB-A-2 303 303, WO-A-97/31629, U.S. Pat. No. 5,776,969, WO-A-98/44924, EP-A-0 714 663 and WO-A-98/11897. The application examples stated and the non-anhydrous preparations described indicate the use or the subsequent formation of paroxetin hemihydrate.
WO-A-97/03670 describes a slow-release form of paroxetin wherein the use of the free base or the hemihydrate is explicitly mentioned.
From U.S. Pat. No. 5,872,132, four different forms of paroxetin hydrochloride anhydrate are known, of which only form C is claimed. Further, in column 7, lines 9-39, there is described in a general form how oral dosage forms can be prepared from this form.
WO-A-99/00131, which is not a prior published document, describes soft gelatin capsules containing paroxetin as a water-soluble solid dispersion.